1. Field of the Invention
The present invention relates to a pixel structure of an electroluminescent display panel, and more particularly, to the pixel structure with the higher aperture ratio and the higher alignment tolerance by adjusting the arrangement of the sub-pixels.
2. Description of the Prior Art
Without a color filter but with the advantage of self-luminous characteristic (i.e., without a backlight module) and low power consumption, an organic electroluminescent display has been regarded as a promising candidate to replace LCD display technology for the next generation display technology for long.
Please refer to FIGS. 1 and 2. FIG. 1 is a schematic diagram illustrating a conventional pixel structure of an organic electroluminescent display panel. FIG. 2 is a schematic diagram illustrating a conventional shadow mask. As shown in FIGS. 1 and 2, the shadow mask 100M with a plurality of stripe openings 100H extending along a column direction Y is employed to perform a vapor deposition process of organic luminescent materials in the manufacturing process of the pixel structure 100 of the conventional organic electroluminescent display panel so as to form a plurality of blue sub-pixels 120B, a plurality of green sub-pixels 120G and a plurality of red sub-pixels 120R on a substrate 110. Each of the blue sub-pixels 120B, each of the green sub-pixels 120G and each of the red sub-pixels 120R are alternately disposed in a row direction X. Each of the display pixel units 120 is composed of one of the blue sub-pixels 120B, one of the green sub-pixels 120G and one of the red sub-pixels 120R disposed adjacent to one another along the row direction X. The blue sub-pixels 120B in each column, the green sub-pixels 120G in each column and the red sub-pixels 120R in each column, which are adjacent to each other along the column direction Y, are respectively formed through one single stripe opening 100H on the shadow mask 100M by vapor deposition processes of different organic luminescent materials. This kind of arrangement of the sub-pixels is generally referred to as a stripe pixel arrangement structure. In this structure, according to alignment precision and fabrication variation of the vapor deposition process, there must be enough space among the sub-pixels to prevent the materials from being mixed in the vapor deposition process and affecting the manufacturing yield. Relatively, there must be enough space among the openings 100H on the shadow mask 100M to ensure enough structure strength. Accordingly, the distribution density of the sub-pixels, in this condition, is limited, thereby restricting the resolution. Moreover, the aperture ratio of each of sub-pixels and the fabrication of the shadow mask 100M are affected negatively.